package com.gy.hadoop.mr.inputFormat;

/*
banzhang ni hao
xihuan hadoop banzhang
banzhang ni hao
xihuan hadoop banzhang
 */

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.KeyValueLineRecordReader;
import org.apache.hadoop.mapreduce.lib.input.KeyValueTextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import java.io.IOException;

/**
 * 统计输入文件中每一行的第一个单词相同的行数。
 * <p>
 * CombineTextInputFormat:多个小文件从逻辑一个切片
 * NLineInputFormat:指定行数放到一个分片中
 */
public class InputFormatMR {
    static class KVTextMapper extends Mapper<Text, Text, Text, LongWritable> {

        // 1 设置value
        LongWritable v = new LongWritable(1);

        @Override
        protected void map(Text key, Text value, Context context)
                throws IOException, InterruptedException {
            // banzhang ni hao
            // 2 写出
            context.write(key, v);
        }
    }

    static class KVTextReducer extends Reducer<Text, LongWritable, Text, LongWritable> {

        LongWritable v = new LongWritable();

        @Override
        protected void reduce(Text key, Iterable<LongWritable> values, Context context) throws IOException, InterruptedException {

            long sum = 0L;

            // 1 汇总统计
            for (LongWritable value : values) {
                sum += value.get();
            }

            v.set(sum);

            // 2 输出
            context.write(key, v);
        }
    }

    public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
        // 输入输出路径需要根据自己电脑上实际的输入输出路径设置
        args = new String[]{"mr/input.txt", "mr/out/inputMR"};

        Configuration conf = new Configuration();

        // 设置切割符
        conf.set(KeyValueLineRecordReader.KEY_VALUE_SEPERATOR, " ");
        conf.set("mapreduce.framework.name", "local");

        // 1 获取job对象
        Job job = Job.getInstance(conf);

        // 2 设置jar包位置，关联mapper和reducer
        job.setJarByClass(InputFormatMR.class);
        job.setMapperClass(KVTextMapper.class);
        job.setReducerClass(KVTextReducer.class);

        // 3 设置map输出kv类型
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(LongWritable.class);

        // 4 设置最终输出kv类型
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(LongWritable.class);

        // 5 设置输入输出数据路径
        FileInputFormat.setInputPaths(job, new Path(args[0]));

        // 设置输入格式
        job.setInputFormatClass(KeyValueTextInputFormat.class);

        // 6 设置输出数据路径
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        // 7 提交job
        job.waitForCompletion(true);
    }
}
